α-Fe 2 O 3 /Ti 3 C 2 T x MXene Heterostructures as Photo-Fenton Catalysts Driving RAFT Polymerization for Ultrasensitive Electrochemical microRNA Sensing
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α-Fe 2 O 3 nanoparticles possess a narrow band gap (~2.1 eV) and exhibit strong absorption in the visible light range, making them promising candidates for photocatalytic applications. However, their poor electrical conductivity, high electron–hole recombination rate, and short charge diffusion length limit their practical performance. To address these limitations, α-Fe 2 O 3 was integrated with Ti 3 C 2 T x MXene to construct a composite photo-Fenton catalyst that drives RAFT polymerization. In this system, the MXene substrate not only disperses α-Fe 2 O 3 nanoparticles efficiently but also facilitates the generation of abundant photoinduced electrons under visible-light excitation. This enhances the Fe 3+ /Fe 2+ redox cycling and accelerates H 2 O 2 decomposition, yielding a high concentration of hydroxyl radicals (•OH). To further explore the functional applicability of this catalyst, it was employed in a biosensing platform for the ultrasensitive detection of microRNA-144. In this design, the •OH radicals initiate RAFT polymerization, allowing for a significant amplification of the electrochemical signal. The resulting sensor exhibits a wide detection range (0.01 fM to 10 pM) and an ultralow detection limit of 4.44 aM. These findings highlight the potential of α-Fe 2 O 3 /Ti 3 C 2 T x MXene composites in photocatalysis, polymer chemistry, and biomedical sensing, offering new insights for future technological innovations.
